Question 1015577
Think about the description for the times.  Don left early going slower, in contrast to Dennis.
Dennis travels only  {{{t}}} hours, quantity of time for catchup.
<pre>
             rate         time         distance
Don           75          t+2           d
Dennis        80           t            d
</pre>

RT=D basic uniform travel rate rule.
If you know this and understand the data table, then you know what to do.